Abstract: An energy conversion device has a self-oscillating transistorized L-C series-resonant half-bridge inverter circuit having alternating resonant inductor current and adapted to deliver a high frequency signal to an effective load coupled effectively in parallel with the capacitor. The device includes a DC voltage supply able to provide DC voltage between the DC terminals; an artificial load arrangement connected to the DC terminals and operable to effectively couple itself in parallel with the capacitor; a load-coupling transformer; and a saturable feedback transformer operable to sense the alternating resonant inductor current and to control and adjust the frequency of the oscillation in proportion to the effective load applied effectively in parallel with the capacitor.

Abstract: An apparatus and method for generating signals. According to one embodiment, the apparatus has an oscillator generating a series of signals, an output stage for transforming the series of signals into a second series of signals, and a watchdog for providing a control signal to the output stage to hold the output stage in a selected state and for changing the control signal to enable the output stage in the selected state when the oscillator generates a first signal of the series of signals.

Abstract: Briefly, to reduce switching stresses, employed is a high-frequency AC power source (110) and a current-limiting (ballasting) network (116). The network ( 116 ) includes a high-frequency trap ( 120 ) and an impedance transforming network (122), which is coupled to the AC power source (110) by the trap (120) and which is for connection to a load that includes at least one gaseous discharge (fluorescent) lamp or other non-linear or negative-resistance load (102). The trap, which has the parallel resonant combination of an inductor ( 130 ) and a capacitor ( 132 ), is resonant at a frequency chosen such that the switching-circuit transistor(s) (210, or 230 and 232, or 250 and 252, or 270 and 272, or 708) of the AC power source (110) switch at times when the level of the current (charge flowing) therein and/or the voltage developed there across is zero, preferably, at a frequency slightly higher than a harmonic frequency of the high-frequency AC power source ( 110 ).

Abstract: The invention pertains to a switchmode DC to AC converter, and particularly to a master-slave half-bridge converter. The slave half-bridge power converter is controlled by a lower power self-oscillating half-bridge master converter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially, for high pressure sodium lamps, completed by a high voltage ignition apparatus. A pair of self-saturated electronically switched transformers controlled by a low power current source provide a power controlled and frequency modulated high frequency ballast for the gas discharge devices.

Abstract: A half-bridge inverter is powered from a constant DC voltage and provides an AC output voltage that is--in contrast with the usual squarewave voltage--describable as being a sinusoidal waveform with the tops clipped off at some fixed magnitude; or, described differently, a waveform composed of truncated sinusoidal waves; or, described still differently, a waveform having trapezoidally shaped half-cycles. This AC voltage is applied across the primary winding of a so-called reactance transformer, whose loosely coupled secondary winding is connected across a gas discharge lamp. The internal inductive reactance of the secondary winding constitutes a lamp ballasting means by way of limiting the magnitude of the resulting lamp current to a pre-established desired level.

Abstract: A circuit for converting on d.c. voltage to another d.c. voltage including a transformer having a center tap and first and second end leads. A d.c. source voltage is connected to the center tap of the transformer. The end leads are connected to ground through first and second MOSFETs and to the gate of the MOSFET through which the other end lead is connected to ground such that the circuit is nominally self-oscillating due to transformer saturation. Current spikes may be minimized with a control circuit, consisting of an oscillator, a flip-flop, and first and second transistors, connected to the gates of the first and second MOSFETs. The control circuit turns the MOSFETS off prior to their natural oscillation turn off caused by transformer saturation. The circuit is particularly suited to operation with a low voltage d.c. source and low voltage MOSFETS.

Abstract: A small fluorescent light turning on power supply device for a liquid crystal TV for operating the back light of the liquid crystal display TV. The invention is characterized in that a resonance type turning capacitor C.sub.S is connected to the light for preventing continuous electric power consumption, coil L.sub.dc is connected between a power supply source and a filter resistor R.sub.S is connected to switching elements, and a capacitor C is connected between the collectors of said two switching elements. According to the invention, an economical small resonance type current source power supply device which is free of noise and switching stress and simultaneously reduces electric power loss to a minimum, can be obtained.

Abstract: A switchmode DC to AC converter, and particularly a master-slave half-bridge converter. The slave half-bridge power converter is controlled by a lower power self-oscillating half-bridge master converter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially, for high pressure sodium lamps, completed by a high voltage ignition apparatus.

Abstract: A switched bridge circuit has semiconductor bridge elements (T1,T2) which are arranged to provide a commutated output from a d.c. source (+300V). The commutation is effected by a switching signal from a control circuit. The control circuit for switching the bridge elements is coupled with the output by a capacitor (C2) such that switching of the bridge elements is prevented while there is a flow of current through the capacitor, the current through the capacitor is indicative of a changing output voltage and a confirmation that the voltage across the bridge elements is not approximately zero or +300V.

Abstract: A lighting circuit for a fluorescent lamp includes a D.C. power supply which is connected across a pair of series transistors. A transformer has first and second windings connected to the bases of respective transistors and a third winding connected between the junction of the transistor pair and a booster transformer. The filaments of the fluorescent lamp are connected through a choke coil to the booster transformer, and a capacitor is connected in resonant circuit with the choke coil.

Abstract: A magnetron is powered via an output transformer TR whose primary winding (a) is connected in series with a resonant converter oscillator circuit comprising an inductor (L) and a capacitor (C3) and switching transistors (T.sub.1, T.sub.2) which are connected to positive and negative power supply terminals and are switched by respective current transformers (CT1, CT2). The switching points of the switching transistors are varied so as to vary the output of the circuit by varying the positive and negative flux excursions in the cores of the transformers (CT1, CT2) such that the net flux excursions are sufficient to saturate the transformers and switch off the switching transistors at a predetermined point in each half cycle. The relative positive and negative flux excursions in the transformer cores are controlled by providing additional windings (g) which are connected to a control circuit whcih rectifies the output of these windings and controls the rectified DC voltage appearing across them.

Abstract: A DC/AC converter for supplying two discharge lamps (12, 13). Two input terminals (4, 5) of the converter are interconnected by a series circuit comprising two switching elements (6, 7). A capacitor (8) connects one of the input terminals (4) to a common end (18) of two output circuits (17, 16, 15, 14; 23, 22, 21, 20), one of these output circuits (17, 16, 15,14) also is connected to a junction point (19) between the switching elements (6, 7). A second series circuit comprising two further switching elements (10, 11) is connected to the input terminals. The other output circuit is connected to a junction point (19.sup.a) between the two further switching elements. The converter thus can be readily used both for simultaneously supplying two lamps and for supplying only one lamp.

Abstract: To provide enhanced starting voltages for fluorescent lamps operating, for xample, from 110 V power networks through a rectifier, and in which a high-frequency oscillatory circuit is used which includes a ring core transformer (TR1, TR2, TR3) operated under saturation conditions, and controlling switching transistors (T1, T2), which have emitter-resistors (R4, R5) connected thereto to stabilize the operation of the circuit and of the transistors, at least one diode (FIG. 4: D4, D5) is connected in parallel to at least one of the emitter resistors; for some circuits (FIGS. 2-4) a diode, or two diodes (D6, D7, D8, D9) can form the emitter-resistors or resistors.

Abstract: In an inverter-type fluorescent lamp ballast, the inverter is powered from an ordinary electric utility power line by way of a rectifier means providing to the inverter a DC voltage having magnitude variations of about plus/minus 30% occurring at twice the frequency of the power line voltage. The inverter's output is a squarewave voltage of frequency averaging about 30 kHz and with amplitude modulations of about plus/minus 30%; which squarewave voltage is applied to a series-tuned L-C circuit. The fluorescent lamp is connected in parallel with the tank capacitor of this L-C circuit, thereby being provided with a current of magnitude proportional to the magnitude of the squarewave voltage. Within a significant range, the magnitude of the lamp current is a sensitive function of the frequency of the squarewave voltage; which frequency is modulated in such a way as to compensate for the variations in lamp current that would otherwise result from the amplitude modulation on the squarewave voltage.

Abstract: An improved oscillator circuit for avoiding core saturation without the need for auxiliary magnetic devices employs an emitter resistance for regulating base voltage, and a semiconductor base shunt for initiating transistor cut-off when the base voltage increases above the threshold voltage of the semiconductor shunt, the emitter resistance being preselected to activate the base shunt before the transformer core reaches saturation.

Abstract: A converter of electric power at a first value of voltage and frequency produces a voltage at a second value and at a higher value of frequency by means of an inverter oscillator circuit having two serially connected transistors. An output power transformer is coupled to the transistors for receiving current excitation from alternate ones of the transistors during alternate half-cycles of the output voltage. Incoming voltage is converted by a diode bridge circuit to a DC voltage which drives the transistors. Serially connected capacitors bypass the bridge circuit to couple high frequency current from a primary winding of the transformer through the transistors. Additional windings of the transformer are coupled in the base-emitter circuit of each transistor for inducing states of saturation during conduction phases of each transistor so as to minimize power dissipation within each of the transistors.

Abstract: A flourescent lamp lighting circuit comprising a rectifying circuit and an oscillatory circuit. The rectifying circuit comprises a rectifier bridge, capacitors and coils to rectify the local alternating power supply to direct power supply and provide rectified electrical power to the oscillatory circuit. The oscillatory circuit comprises two transistors and an L-C circuit which, taken together, form an astable circuit which generates and maintains oscillations. The frequency of the oscillations is determined by the nature of L-C circuits. The ON's and OFF's of the transistors are controlled by induction coils within which currents are induced by the variation of magnetic flux in the inductor coil of the L-C circuit. The high frequency oscillations in the oscillatory circuit induce high frequency electrical signals on a secondary coil which then lights the fluorescent lamp.

Abstract: An oscillator circuit for generating a square wave output for space or terrestrial applications comprising a main oscillator and a saturable transformer forming the feedback loop of the power inverter. According to the invention, a synchronization circuit comprises transistors for shortcircuiting respective branches of the primary winding of this transformer upon detection of signal from differentiators connected to the main oscillator. Means connects a main limiting resistor to the center tap of the primary winding so that flux inversion is effected in the saturable transformer at the end of a power inverter recovery time.

Abstract: A lighting apparatus for an electric discharge lamp includes a lighting ballast capacitor connected in series to an electric dicharge lamp for stabilizing a lighting current to the lamp; a preheating ballast capacitor connected in parallel to the lamp for supplying a preheating electric power to the lamp; electric power supply including an output transformer for supplying an electric power to the lighting ballast capacitor; a control electric power supply circuit for obtaining a control electric power through the lighting ballast capacitor and discharge lamp or the preheating ballast capacitor without adding a stepdown transformer or a resistive element for voltage drop; and an oscillator which receives the control electric power from the control power supply circuit and controls the electric power supply. With this lighting apparatus, the electric power loss is made small and the miniaturization of the apparatus can be realized.

Abstract: High-efficiency inverter circuits, particularly half-bridge devices, are especially suitable for energizing gas discharge lamps. The inverters preferably employ a series-connected combination of an inductor and a capacitor to be energized upon periodic transistor conduction. Transistor drive current is preferably provided through the use of at least one saturable inductor to control the transistor inversion frequency to be equal to or higher than the natural resonant frequency of the inductor and capacitor combination. The inverters can develop high output voltages to supply external loads connected to the inductor-capacitor combinations.

Abstract: A push-pull inverter is supplied from an inductively current-limited DC voltage source by way of a center-tap on a transformer having significant inductance. This transformer inductance is parallel-coupled with a capacitance means. The inverter is made to self-oscillate through positive feedback provided by way of a saturable current transformer. The inverter frequency is determined by the saturation time of this current transformer, which saturation time is designed to be longer than the half-cycle period of the natural resonance frequency of the transformer inductance combined with the capacitance means. The resulting inverter output voltage may be described as a sequence of substantially sinusoidal half-cycles interconnected with periods of zero-magnitude voltage. By controlling the length of the saturation time, the effective magnitude of the inverter output voltage is controlled, thereby permitting control of the amount of power provided to a load connected thereto.

Abstract: An inverter circuit having an output power transformer if provided with a replica driver transformer which is a miniature "clone" of the power transformer. The replica driver transformer uses the same core material as the power transformer and is designed to saturate before the power transformer thereby shutting off the drive to the power switching transistors and saving them from burn out which might otherwise be caused by power transformer saturation. Reset circuits can be included as part of the circuit to assure successful start up preventing first-half-cycle-instant-burnout-syndrome occurrence.

Abstract: Disclosed is a system for supplying high frequency alternating current to gas discharge lamps, such as fluorescent lamps, and the like and a unit that can be placed in or adjacent to a lighting fixture to convert a direct current supply into high frequency AC and also to provide the ballast needed for operation of the gas discharge lamps. A preferred inverter network includes a symmetrical, class B, push-pull current-limited, tuned-collector, sinusoidal oscillator which is self starting, highly efficient and stable over a wide range of input voltage, with or without load. Circuits are disclosed for dimming the lights, for supplying heating current to lamp filaments at high voltage at the start and much reduced voltage after the arc has been struck in the lamps served by the ballast unit, and this reduction in filament current takes place automatically without switches, resistors or other expensive and energy consuming means.

Abstract: A blocking oscillator contains a switching transistor which is driven by an integrated circuit. This circuit receives its supply voltage during the blocking phase from a winding at the primary side. A further winding at the primary side supplies the regulating variable for the integrated circuit during the flow phase. The supply input of the integrated circuit is connected by way of a further transistor and a diode to the control winding and a Zener diode biases the base of the further transistor. In the start-up phase in which the voltage of the supply winding (control winding) is built up, the circuit supplies the required operating voltage and switches off again in the steady state of the power unit.

Abstract: A single power transistor oscillator circuit includes a single transistor oscillator coupled by an inductive means including an inductive coil and transformer to a DC potential development means with a wave-shaping means coupled to a secondary winding of the transformer to provide a substantially symmetrical AC potential centered about a zero level DC voltage and applied to a load circuit.

Abstract: The converter comprises an output transformer (T1) through which pass trapezoidal current waves. The primary winding (A0) is supplied under the control of two control circuits (P1, P2), each comprising a transistor (Q1, Q2) and a diode (D1, D2) which are connected in anti-parallel. The two transistors are controlled by two oppositely-poled secondary windings (W1, W2) of a second transformer (T2), the primary winding (W3) of which is controlled by the first transformer (T1). Associated with each control circuit (P1, P2) is a capacitor (C1, C2) such as to accumulate energy during one phase of operation and to discharge it during a subsequent phase. Another winding (Wc) of the second transformer (T2) permits the latter to be biased, stabilizing the output voltages by means of closed-loop feedback control of one thereof.

Abstract: An inverter (100) receives a DC voltage and generates therefrom a square wave output signal. The inverter includes an output transformer (T3) and a saturable core transformer (T4). The saturable core transformer (T4) provides base current for a first transistor (Q3) and a second transistor (Q4). The first transistor (Q3) and the second transistor (Q4) alternatively turn on and off, causing a square wave to appear across the secondary winding of the output transformer (T3). The primary winding of the output transformer is coupled to the collectors of the first and second transistors via a pair of windings (L10, L11) magnetically coupled to the saturable transformer (T4). A pair of diodes (D4, D5) are provided to prevent the output leads of primary windings of the output transformer (T3) from dropping below ground potential.

Abstract: A switching circuit apparatus driven by a relatively low DC power supply voltage, which includes a power supply terminal designed to receive a DC power source voltage, a pair of switching circuits comprising switching transistors (28, 30 and 32, 34) connected in parallel with each other and connected to the power supply terminal, first circuit means (10,12) connected for supplying the respective switching circuits with a switched signal, and a second circuit means (16, 18, 40, 14) connected for supplying the respective switching circuits with a pair of control signals which are opposite in phase and which are never both at a potential difference other than a prescribed potential at the same time. The switching circuit transistors (28, 30 or 32, 34) are all fully conductive prior to any transition in which two are rendered non-conductive by the control signals, thereby enable operation of the circuit with low power consumption.

Abstract: A D.C. to A.C. inverter using switching transistors driving a multiple-core transformer which includes a high-permeability saturable core upon which both the primary and secondary windings are wound and one or more lower permeability non-saturating cores upon which the primary and/or secondary windings are wound to provide additional self-inductance. The inverter switching transistors drive the two halves of the transformer's center-tapped primary winding on alternate half-cycles under the control of a feedback winding which is wound on the saturable core. A non-saturating core about which the primary winding is wound, and a capacitor connected in parallel with both halves of the primary winding, protects the switching transistors against transients, prevents the saturating core from going into hard saturation, and efficiently transfers energy stored in the leakage inductance of the primary winding from half-cycle to half-cycle.

Abstract: An electronic ballast for a discharge lamp (8) for restricting and stabilizing the lamps current. The ballast comprises a high frequency oscillator for connection to a D.C. supply which consists of two transistors (1,2) connected in series, with a base drive transformer (3) coupled between them to bring the transistors (1,2) into alternating phase operation. A resonance circuit connected in series with the primary winding (4) of the transformer (3), comprises an inductor (7), resonance capacitors (10 and 11) and a capacitor (9) coupled in parallel with the lamp (8). The lamp (8) is, in turn, connected in series with the resonance circuit. In addition, a filter capacitor (c) having a high charging ability is coupled between the terminals of the D.C. supply. The resonance capacitors (10 and 11) are connected in series between the terminals of the D.C.

Abstract: An electrical converter for supplying electrical power to a load from a d.c. source and which includes semi-conductor switching means for converting a direct input current to an alternating current and output transformer means fed with the alternating current for changing the magnitude of the output voltage with respect to the input voltage, wherein the semiconductor means includes transistor means connected with a drive transformer means in a configuration which provides for switching in response to saturation of at least a part of the drive transformer means, and the drive transformer means includes a winding connected in the main current circuit of the transistor means in a configuration providing current feed-back to a drive branch of the circuit connected to a control electrode of the transistor means to increase the response of the transistor means to drive signals derived from the input current and effectively provide a forced D.C.

Abstract: An arrangement for starting and supplying a discharge lamp (14) equipped with preheatable electrodes (15, 16). An electric coil (13) is arranged in series with the lamp and a capacitor (17) is arranged in parallel with the lamp. A voltage of a high frequency is first applied between the ends (A, B) of the series arrangement formed by the coil (13) and the lamp (14) whereafter approximately 1 second later said frequency is reduced until a series resonant condition is obtained and thereafter still further reduced to the operating frequency of the lamp. This starts the lamp (14) with the electrodes preheated to a sufficient extent.

Abstract: A self-oscillating inverter circuit wherein the inversion frequency can be controlled by way of providing a controllable flow of electrical power to a resistor heating means that is thermally coupled to a saturable magnetic ferrite transformer used in the inverter's positive feedback loop. By way of its saturation characteristics, the saturable transformer determines the inversion frequency. These saturation characteristics are substantially influenced by temperature; which therefore provides the basis for controlling the frequency by controlling the flow of electrical power to the resistor heating means.

Abstract: An electronic ballast for energizing fluorescent lamps comprising a converter including a rectifier and a filter for converting an alternating source voltage into a direct current voltage, a network including first and second switching transistors, a tank circuit having a primary winding of a transformer, a secondary winding of the transformer for providing feedback of a portion of the voltage developed across the tank circuits and a bias circuit coupled between the opposite ends of the secondary winding and the emitters of the transistor for alternatively applying bias to the transistors, the network serving to convert a direct current voltage into an amplified sinusoidal voltage having a high frequency, and fluorescent lamps connected in a series configuration coupled across the primary winding.

Abstract: A high efficiency push-pull inverter circuit employing a pair of relatively high power switching transistors is described. The switching on and off of the transistors is precisely controlled to minimize power losses due to common-mode conduction or due to transient conditions that occur in the process of turning a transistor on or off. Two current feed-back transformers are employed in the transistor base drives; one being saturable for providing a positive feed-back, and the other being non-saturable for providing a intermittently negative feed-back.

Abstract: A high efficiency push-pull inverter circuit employing a pair of relatively high power switching transistors is described. The switching on and off of the transistors is precisely controlled to minimize power losses due to common-mode conduction or due to transient conditions that occur in the process of turning a transistor on or off. Two current feed-back transformers are employed in the transistor base drives; one being saturable for providing a positive feedback, and the other being non-saturable for providing a subtractive feedback.

Abstract: A self-oscillating DC to DC converter which includes either two or four transistors, three transformers (a converting transformer, a driving transformer and a current transformer) and an inductance.The operating frequency of the converter is fixed by the saturation time of the driving transformer. The base currents of the transistors are mainly supplied by the current transformer so as to be in proportion to the collector currents of the transistors. The operating frequency of the converter is kept constant in spite of load fluctuations. The inductance which is connected in series between a winding of the converting transformer and a winding of the driving transformer. The inductance prevents the two or four transistors from being `on` simultaneously.

Abstract: An electronic ballast employs an electronic inverter which drives a main power transformer across the output of which terminations are connected for a plurality of fluorescent lamps. A high impedance capacitor is connected in parallel across at least one and less than all of the fluorescent lamps. An auxiliary transformer is interposed between the output of the main power transformer and the cathode elements of the fluorescent lamps. Upon start-up, the high impedance capacitor initially creates a bypass around lamps with which it is connected in parallel to thereby apply the entire high voltage output of the power transformer to start the remaining lamps. Once these lamps are started the voltage drop thereacross is reduced to allow the high voltage output to bypass the high impedance capacitor and start the lamps connected in parallel therewith. The auxiliary transformer provides good magnetic coupling and low voltage to the cathode elements of the fluorescent lamps.

Abstract: A power supply including a high frequency inverter circuit coupled to an electron discharge lamp load through a special purpose transformer is disclosed. The transformer is wound on a saturable ferromagnetic core structure forming a first magnetic flux path coupling the primary and secondary windings of the transformer and a second shunt magnetic path including an air gap which carries and increasing share of flux as load current increases. The switching of the inverter circuit occurs in response to the partial saturation of the core. Auxilliary windings serially connected with the primary winding of the transformer and wound about the shunt magnetic path enhance the current regulating properties of the supply.

Abstract: An electronic ballast system includes a first capacitor (C.sub.2) electrically coupled to the first filament (30) of a gas discharge tube (12) and becomes the power supply of the gas discharge tube (12) subsequent to both its charging and discharging operations. The collector (38) of a transistor (Tr) is connected to the first capacitor (C.sub.2). The primary winding (22) is connected to the first capacitor (C.sub.2) and the collector (38) of the transistor (Tr) in parallel relation. The transformer (t) includes a secondry winding (24) which is connected on opposing ends thereof in feedback relation to the base (44) and emitter (42) of the transistor (Tr). Pulses of opposing current polarity (122 and 124) generated through the secondary winding (24) alternately provide conducting and non-conducting states for transistor (Tr) to discharge and charge the first capacitor (C.sub.2) through gas discharge tube (12) to provide a power source for operation of gas discharge tube (12).

Abstract: A switching system for delivering pulses of power from a source (10) to a load (20) using a storage capacitor (C3) charged through a rectifier (D1, D2), and maintained charged to a reference voltage level by a transistor switch (Q1) and voltage comparator (12). A thyristor (22) is triggered to discharge the storage capacitor through a saturable reactor (18) and fractional turn saturable transformer (16) having a secondary to primary turn ratio N of n:l/n=n.sup.2. The saturable reactor (18) functions as a "soaker" while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor (C4) charges, and then switches to a low impedance state to dump the charge of the storage capacitor (C3) into the load through the coupling capacitor (C4).

Abstract: A self-starting transformer-coupled FET multivibrator is constructed to avoid net dc flow in the primary winding of its transformer, driven push-pull by the multivibrator FET's.

Abstract: Apparatus for producing spark ignition of an internal combustion engine in which sparks at the spark plugs are initiated by a high voltage pulse of typically 20 KV and are sustained thereafter by a d.c. voltage of typically 3 KV. In one embodiment the d.c. voltage is produced from a 12 volt supply by a d.c. to d.c. converter, the converter being adapted to produce a substantially constant voltage irrespective of the current drain produced by the spark, within given limits. The converter is also adapted to shut down its operation in the event of an output short circuit. The converter is disclosed connected to a lean burn PROCO engine with the result that only one spark plug per cylinder is required. In an alternative embodiment the d.c. sustaining voltage is derived directly from a conventional alternator driven by the engine.

Abstract: A Royer circuit, which includes an inverter and a saturating output transformer, is powered from a current source rather than from a voltage source, thereby reducing transistor current overshoot when the output transformer saturates. A current source inductor and a PWM (pulse width modulated) power transistor are series connected in the current return line of the inverter. The PWM power transistor emitter is connected so that potential between it and the common DC input power terminal will be low. This permits the PWM power transistor to be direct-coupled from a low voltage PWM switched mode power supply control circuit. A start-up circuit for supplying start-up power to inverter control circuitry from the DC input source is provided. Feedback loop control for the PWM power transistor is also provided.

Abstract: A transformer coupled, resonant feedback, tuned oscillator circuit in which the output current to a low power variable load is maintained constant by incorporating into the circuit an additional feedback circuit which provides a DC error voltage to the oscillator circuit enabling it to compensate for variations in core loss resistance, variations in load, and variations in other circuit parameters. The feedback circuit includes two separate electronic switches both of which are connected to a voltage averaging circuit and an error amplifier which compares the voltage of the averaging circuit against an adjustable reference voltage whereby the DC error voltage is generated and supplied to the center tap of the transformer feedback winding. Because oscillator transformer core resistance variations can be compensated for, the design of the oscillator transformer can be simplified and readily available, not specially designed, transformers can be utilized.

Abstract: A power transformer of an inverter power supply has a primary winding coupled to a source of DC voltage. First and second transistor switches are coupled to the primary winding in a push-pull arrangement. A drive winding of a saturable transformer is coupled to the base electrode of each of the two transistor switches to alternately apply forward drive to each switch. A control winding of the saturable transformer is supplied with a control current that reaches a magnitude that magnetically saturates the core of the saturable transformer to remove forward drive from the conducting transistor switch for developing an alternating polarity output voltage across a supply winding of the power transformer. A capacitor and an inductor form a resonant circuit upon attainment of core saturation.

Abstract: The invention relates to static converters of the symmetrical type whose function is to convert an input direct current voltage into an output alternating current voltage of chosen frequency and power. The self-oscillator according to the invention is composed of two transistors mounted with a common emitter. The device is energized, for instance, from a main power supply unit, associated with a voltage limiter circuit, which subjects the output power of the device to any parameter. The capacitive power factor of the device is compensated by an inductance connected in series with the main power supply. The device according to the invention can replace, advantageously, the conventional "ballast" for fluorescent lamps.

Abstract: Described is a circuit to invert DC to AC for the operation of electroluminescent lamps. A primary winding of a transformer is in series with a power source and the input or output of the switching device. The output of the switching device is connected back to the power source. The secondary winding of the transformer is in series with an electroluminescent lamp and the controller side of the switching device. The secondary winding doubles as both the output to the electroluminescent lamp and the feedback winding to the controller side of the switching device. The electroluminescent lamp doubles both as the load and limiting impedance to the controller side of the switching device. Also described is a unique device for dimming the electroluminescent lamp.

Abstract: A power inverter oscillator circuit has an output transformer with a primary winding, coupled in parallel with a capacitor, and the opposite ends of which are connected to the respective emitters of a PNP and a NPN transistors. The collector of the NPN transistor is coupled to the positive terminal and the collector of the PNP transistor is coupled to a negative terminal. In addition, a switching transformer is provided having a primary coil coupled at one end to one terminal and at the other end to the emitter of the transistor which is coupled to the other terminal. The switching transformer has two secondary coils or windings wherein one of the secondary coils is coupled between one terminal and the base of the transistor whose collector is coupled to the other terminal and the other secondary coil is coupled between the base of the other transistor and the remaining terminal.

Abstract: High efficiency push-pull inverters minimize undesirable energy losses usually resulting from simultaneous conduction and imperfect switching of the transistor switching means. In each of the disclosed circuits, a saturable inductor and a diode are connected in parallel and across the base-emitter junction of each transistor. Voltage on the base of each transistor causes its associated saturable inductor to saturate, and the saturated inductor then terminates the flow of base current and provides a path for rapid evacuation of the charge carriers stored in the transistor base-emitter junction in order to render the transistor rapidly non-conductive. Each diode provides a drain path for current continuing to flow through its associated saturable inductor after junction evacuation. A novel triggering means initiates oscillation of the inverters.